Back to the origional topic,
£10/hr extra for the T.L. is not much money in the PPL, and £95/hr is a GOOD rate IMHO, the question that needs asking is why is the school INSISTING on this for someone who is going to carry on with a PPL, this actually makes me suspicious of the schools attitude and would steer me to another one, ask what extra do you get for the £10 - maybe do give you a log book or they can knock it off the membership if you go ahead, otherwise tell them you will DO the trial lesson BUT, only if they charge you NORMAL rates .
If they STILL insist on the extra £10 I should go elsewhere, not because of the money but because of the attitude.