YMCA is probably the largest gym in London with again, probably the largest swimming pool in central London I have ever seen (and trust me I have been to lots of gyms in central London). The reception is on the ground floor and when I arrived was a bit crowded with the staff a bit 'all over the place' in a bad way but despite this you could sense they were just trying their best. From the reception area you can see to one side, through glass a small cafe and further the massive swimming pool where sauna and steam room are also located. Passing the barriers at the reception and getting my towel for which I paid £1.00 (as a non member with reduced day pass I got from 'pay as you go gym') I descended two floors underground to reach the massive changing areas where lockers function on returnable £1 coins. Lots of mirrors everywhere with hair driers and even hair straighteners but no plastic bags to put your dry swim suit (there is a small drying machine though). This gym is centred around a large open space where you can play badminton/volleyball etc and having to one side a 'heavy area for the boys' and to the other side the machines targetting all kind of muscles and some running machines, plus separate glass rooms for cycling etc where classes are being held.
On the first floor there are more running machines/cross trainers etc and to one side a matt/ball area probably designed for ladies or those into yoga.
The gym is simply massive and could have been perfect but due to the location close to Tottenham Court road you see some characters that probably would give you thrills if you were to meet them on the streets of Soho.