Some good news on the overspray today. Followed the advice of the paint shop bloke and did a mix of 50/50 ,alcohol and Mineral turps. Put the mix on a cotton wool bud and rub on tank and every rub took a little more over spray off. Success, looks great, then gave the tank a good wash, paint on tank looks fine.
Next went to tackle the seat and a lot more difficult. Paint seemed very slow to soften, so good or bad, got out some 0000 grade steel wool, dipped in the mix and just wiped back and forth gently, gradually soften and removed the paint. I then wipe the seat over with straight alcohol to help remove any mineral turps.
Next washed the seat with a hot soapy sponge. I noticed that still a few small specs left but the sponge was taking a few of them off. So then got a nylon stiff brush, wet the seat and scrubbed, got nearly all the rest off. I would say 98% specs now gone so pretty happy. I did notice while wiping the seat with the cotton wool bud, did lose some colour. When seat dried, were a few lighter coloured flat spots, so sprayed on a vinyl, rubber renewer and the seat looks like new, so pretty happy with the outcome.
I know probably not the best method on the seat, but time will tell if the vinyl falls to bits, but the seat looks great.
Again thanks for all your suggestions.