Whatever Airtours or any other travel company charge you for your day trip to Gibraltar can be done much, much cheaper by taking a local tour run from one of the many shops in the tourist areas along the CdS, the large tour operators althought providing you with a service are of course out to make money. The reason for your 'welcome meeting' being at the first available time at the beginning of your holiday is so that you don't have a chance to find out for yourself what prices are being offered locally, and you can always add yourself to one of their tours afterwards when you have had a chance to compare with the deals offered in the 'high street'.
The time taken to get there all depends on where you are staying on the CdS and how many pick ups the coach is making, but I suppose an hour to an hour and a half would see you there...as to how long you get that again depends on the operator.
Be warned...Gibraltar is not on the whole a cheap shopping trip...cigarettes (about �6 for 200 depending on the brand) and spirits are but if you are thinking on having a meal expect to be shocked .. we regularly see places offering fish & chips with a cup of tea for �9.95, and a can of coke over �1 - bargain!! and expect to pay a hefty sum to do the 'tour'. As Gibraltar is still British they use stirling but will take your euros and give you change in stirling and their exchange rate is mean to say the least so do keep some ���'s to spend if you are planning a trip.
Reading between the lines you can see I am not enamoured of the place but realise its a trip you expect to do whilst staying nearby..we live 60 miles away and only go there once a year or so when the call of Marks and Spencers becomes too much to bear!