I was in Hammamet for a week 25 June-1st July and then in PEK for another week 1st July-9th July.
Still not sure how much have we spent (2 adults) as my OH developed some obsession with jet ski, quads,paragliding and done all a few times
I got very friendly with "a few" coctails that I have not tried before.
We have not done any trips as I have done them all (got all t-shirts LOL) before any did not fancy them again and OH did not want to go on his own.
I just remember one meal at Sidi Slim took as back about 90 dinars but what an experience
We were on HB in both Bel Air (Hammamet) and Kanta (PEK) but overslept a few breakfast times (especially after staying till God knows what time in British Bar opposite Bell Air) and skipped a few dinners prefering to go out to eat something more Tunisian than the hotel food.
Generally we drunk local stuff (my favourite Tibarine and coke and OH attached to Celtia), had lunch at the beach about 20 DT for 2 (with a plate of fresh fruits and drinks of course) and did not count the money while there.
Realistically, 300-400 should be more than enough for a week for 2 people. You are ok to take cash with you just remember to only change for dinnars as you need them, even on the daily basis as later on you can only change a little bit back and changing back into sterling will cost you 30% in comission.
Also, remember the tips - 1 or 2 dinnar seems to be a norm for the maids/waiters etc. They are on average 10 dinnar a day wage so whatever they get in tips is always appreaciated.. and shown for example by flower petals all over your bed/room floor when you get back from the beach or an extra roll of toilet paper
Enjoy..... I only got back this Sunday and miss the place alreadyyyyyyyyy