Hi Londoner
I have trained with Clive for 5 years, and have resisted jumping into this thread because any opinion I give on his teaching would obviously be biased.
But, since you seem to have decided on the WSL school, I can emerge. 
He and Anthony have both trained in WC for over 30 years, and are the only teachers authorised by WSL to teach his method in the UK. (Nino, formerly of The Basement, has now retired to Foreign Parts )
I would rate their teaching extremely highly, and I have seen a lot of WC both here and abroad. They encourage a questioning attitude towards what they teach, they feel it important that you do it the WSL way not because they tell you to do it, but because it makes sense for you to do so. Clive often says that if someone can show him a more simple, direct, or efficient way to fight, he will learn it. He has not found it yet.
St.Albans classes cost £6, and are at 12-3 Saturday, and 7.30 onwards on Monday. There are no gradings, fees or otherwise, apart from a annual membership fee of something like £10-20. You get a tshirt when you join. No fancy gear, just wear what you want, trainers, shoes, shorts, jeans, whatever you feel comfortable with.
Clive handles the teaching for the St.Albans school, and his senior instructors do the schools in Brighton and Luton.
Anthony takes less of an active part in the classes these days due to health problems, but still does private lessons. Clive has a busy schedule of private lessons, which cost £25 an hour.
The teaching is relaxed and informal, because that was the way Wong used to teach in HK. There is no bowing, making the palm fist gesture, or calling Clive “sifu”. As Wong used to say, we are living in the 1990s, not the 1890s!
The training starts off with the 1st form, a lot of attention is spent on the concepts behind this, rather than particular techniques. Then single hand chisao, on to rolling, simple attacks, and eventually full chisao, which leads after a lot of experience into what others would call sparring. Clive is happy to teach at the pace an individual can learn, so there is no rigid timeframe that has to be kept to. If you are a fast learner, you can take advantage of this.
The WSL way, as you no doubt know if you have read about it, emphasises directness and simplicity. It is not a defensive style, but very aggressive, as Wong believed from his Beimo experience that attack was the best defence. When you get more advanced, the chisao gets hard and fast, and you do get the occaisonal cut lip or other minor injury. Thems the breaks.
What else can I say? Oh yeah, Clive makes rubbish jokes. And is the only Wing Chun instructor I have ever met who can a) make a joke at his own expense, b) laugh if someone else makes a joke about him.
Its a good club to join if you like travel! Clive has encouraged the growth of several schools in Europe, and often takes students over there for weekend seminars.
A bunch of students have just come back from Barcelona, before that was Stuttgart, and Clive himself has just nipped off to San Diego for a week to see some students over there. There are also regular seminars in Lansarotti, Athens, and of course the UK.
And of course, there is the piece de resistance, our annual Hong Kong trip in November, started after the 1st Conference. 10 days of training, eating, drinking and clubbing, (and chatting up girls, for the single guys amongst us) all for the princely sum of ~£600. We had 25 go out last year, and should have more this year.
Hope this helps. If you need any more info, let me know.
Hope to see you soon.