I can assure you that you'll be most welcome to come and have a guided tour of the
British Airways Flying Club - just PM me and let me know when you want to visit - engineering department included!
As others have said, be very careful of hidden costs (one company mentioned is very good at hiding 'extras'), be it membership, landing fees or fuel surcharges. Don't forget to get a look at the actual aircraft you'll be flying, you may find some are better kept than others...