Hey, we booked our wedding through Thomas Cook and got married in mexico on 14th April this year at Aventura Spa Palace. They told me I was dealing with a wedding specialist, but to be honest she wasn't able to answer most of our questions (We only had a simple wedding bear in mind)...
So from experience I would say that the booking of the holiday and wedding, (which was free - keep an eye out for deals, there are lots) was fine, but if you want to know the finer details like costs of extras, whats available for menus, cakes etc, choose your hotel and email the wedding planner directly (email the hotel from their web page)
This was the simplest and most accurate way of geeting up to date info. before we went I knew exactly how much any extras were, what was and wasn't included and could give the planner time to get us exactly what we wanted.
The wedding and holiday was amazing and the hotel itself was stunning, we can't wait to save up enough again to go back!I would recommend getting married abroad to anyone, we had a wonderful time at half the price of a wedding at home.
Hope this helps,