I used Puffin Insurance & hubby had his with Good to Go. You could try those for an online quote or use a comparison website such as:-

https://www.moneysupermarket.com/travel-insurance/pre-existing-medical-conditions/

it is not the best idea for a couple to use different insurance companies on the same trip. although it can appear to save money this could all be negated in the event of a claim.
if, as is normal with a couple, you split your clothes between 2 cases and one goes missing or gets damaged you then have to claim of both policies and have two excesses.
it gets worse in the event of illness where the insurers of the person injured/sick will not normally cover any of the expenses of the partner if an extended stay in hospital results in a missed flight or extra hotel expenses for example.
the only way to get round the illness issue is to declare all medical info for both partners to both insurers and this negates the idea of getting separate insurance.
when taking out any travel insurance you need to look at all the risks including, death/illness/missed flights/health of family members not travelling/health of those travelling and declare these to the insurers.
you could make a concious decision to self-insure these things that are unlikely to happen and would not cost too much to remedy; with a short haul trip within the EU you could use your EHIC card for hospitals and cheaply replace clothes lost or get a cheap flight home and so not need insurance at all as your home contents insurance would probably cover you for some of the clothes lost/damaged but you do need to have sufficient funds to cover you to do this and is not something i would recommend for the majority of people.
bear in mind that places like in Spain and Cyprus you are likely to be sent to a local clinic as a matter of course, rather than a NHS hospital, so you have to be aware of this and insist on going to the NHS hospital, if you can, or end up with horrendous costs.
with insurance you tend to get what you pay for and cheapest is not normally the best - the excesses are normally very large and the exclusions many.
lecture over
for the OP have a look at Post Office insurance as they can sometimes be very competitive for pre-existing illnesses.

Hi Jim we have holiday insurance cover with Nationwide & home insurance cover for abroad. What happened was, hubby has a couple of medical conditions, diabetes & HBP both tablet controlled, neither were covered by Nationwide insurers. I got him covered through GTG.

Just before we were about to leave for our hols I realised that I wasn't covered for cholesterol, I just needed basic cover for this & Puffin came out the cheapest so booked with them.

So, are you saying that say I didn't have a medical condition & just got hubby covered for his & I only had Nationwide cover, that if hubby was ill I wouldn't be covered by his policy to stay with him? If so, does this mean I'd have to put the 2 of us on his policy when only one would need the extra cover?

We usually only travel to Europe (Canaries) & take our EHIC.

Glynis,
your holiday insurance will only cover the named person(s) on the policy.
if you have separate policies and you end up in hospital then only you are covered for the expenses associated with your stay. your partner would normally have no claim on your policy but could try and claim of their own policy, but if you had any medical history that they had not declared on their policy the insurers would rightly decline to pay.
there are some policies that will cover you for someone traveling with you (or even for a relative's death/injury that prevents you traveling) but these will usually be at the more expensive end of the market and the insurer would insist on full disclosure before starting the policy.
i presume you have the free cover with Nationwide for both of you but they have declined to cover hubby's conditions and so you needed to cover these under a different policy. in this case, anything that happens to hubby related to his conditions would not be covered by Nationwide, for either of you, and only by GTG.
you would need to check the T&Cs of the GTG policy to see if it provides any expenses for you if hubby has a problem.
if Nationwide refused you cover for cholesterol, then you need to check the Puffin T&Cs as well.

i have used the Post Office in the past, and Insure & Go, who both offer reasonable cover for diabetes, HBP and cholesterol. try a dummy run on the PO site and you may be able to get a quote at nigh on ordinary rates if your conditions are under control. it may be worth taking out the policy with them and ignoring the Nationwide cover.

I am surprised Nationwide declined cover for Cholestrol Glynis. Are you on medication for it most over 50s these days seem to be on Srtatins as am I. I did consider opening a Nationwide account that offered free holiday cover and rang there insurers I could have got the cover for an additional fee which wasnt too expesive. However I decided the account wasn't for me so never proceded. I am sure there will be thousands of people with these free accounts who never read the terms and conditions so never declare there medical history not realising that if they make a claim the insurers will contact their GP for medical information.

I have a Nationwide account and all it took for my wife to get insurance was to declare her blood pressure and cholesterol medication and pay the addiction fee.

Thanks Jim 👍

The first people we contacted for pre existing medical conditions was the Nationwide insurers. They would cover us but only as an annual policy.

We are away next year for 3 weeks, I'll price up the annual Nationwide cover against both of us on a separate policy 👍

Nickmac, I always tell them on the phone that I've declared every tablet, doctors visit etc as I don't want to fall & break my leg to be told they won't pay out as I'd been to the GP 4 months ago with a cold 😁

That's another point folks should bear in mind, if, after you've got your insurance & you need any treatment, inform your insurance company!