Thanks everyone for your help and comments.

We eventually got a response from a tour operator in London who was able to give us a deal on 11 rooms for a decent rate. But, the outstanding issue that still gives me a headache is air travel to London.

newgroundhogbrit, the problem here with Italy is that customer service care plays a very distant second to making money, especially in this economic climate, and from all the emails we have sent out, the only travel agencies to have responded have insisted we speak to BA in order for us to secure group travel discounts (which should be valid for travel to and from the UK according to their website).

Ultimately, i'll keep searching - i'm sure i'll find one agency that can supply us with what we need specifically.

Thanks again everyone!