Hi

You can find a lot of information regarding currency in this existing topic http://www.holidaytruths.co.uk/viewtopic.php?f=27&t=144249

Finally!!! is it best to take sterling and exchange this into local currency whilst in resort / hotel !

A quick answer is that it is a closed currency and you can only get the Dinar in Tunisia, so you have the choice of Sterling (Cash, English notes only), travelers Cheques and changing in resort / hotel or using your debit / credit card and getting money from one of the plentiful ATM's.

I realise trousers are required in the restaurant at evenings, will smart jeans suffice?

Yes they would be fine
Sorry I can't specifically help with the towels other than to say that nearly all tourist the hotels in Tunisia provide towels for the beach/ pool and you exchange them as required. if for some very strange reason they don't (I am sure they will) you can buy towel out there cheaply.

Graham

Hi, small tip for you regarding currency.
You can exchange your currency to dinar in any bigger hotel. The rate is pretty much stable.
Don't exchange all the money you brought as dinar is closed currency, it's not allowed to take them home, also when you try to exchange them back on airport they will give you silly money.
I only exchange them in small amounts as ther is no benefit or higher rate when you do it in bulk.
Michal