Those who've read my posts in 'Motoring' will know that I used to deliver cars for a living. Once I'd delivered them, however, I had to use public transport to get to my next job, so I've probably used buses in almost every area of the UK.
Based upon my experience, I would estimate that 'exact fare only' applies to well over 50% of all bus routes in the UK. (Knowing this, I always carried plenty of change!).
In some areas, e.g. Ipswich, you can get 'change' in the form of a 'credit ticket' which can either be converted to cash at the bus station or, more usually, used as payment towards your next ticket.
Anyway, if your fare was only 80p, you were lucky. In many parts of the UK the minimum fare (just for one stop) is well above �1. (Hampshire always seemed to have the highest prices to me). If you happen to be travelling near to a main airport, and make the mistake of getting on a bus which serves the airport, you'll probably pay much more. (Hop on the X22 in Essex and you can find yourself paying �5 just to go a couple of miles down the road - It's just because the bus serves Stansted so they charge 'airport prices'!).
Chris