You ask/you answer: I'm a mechanical novice, so should I buy my next bike from a dealer?

Buying privately, check the service book, and better yet, the receipts identifying what work has been done. If it's got something like "fitting helicoil" suggest you walk away.

Buying privately or from a dealer, look at the technician who serviced the bike. If you wouldn't trust him walk away. If he seems patient, careful and fastidious, it might be a better bet.

Don't be scared of higher mileage bikes. High mileage bikes in good condition have been enjoyed and haven't been sat in the garage waiting for bits.

Get the bike checked to see if it's stolen.

dealers can add up to £2000 to the possible private purchase price of a newer bike. Smaller cc bikes or older models can be £1000 more from a dealer and a fair bit of that pays for a warranty package...overall buying a bike depends on you. can you pay cash can you service / repair it yourself do you have alternative transport. If you can say yes to these then buy private and just look for a recent service history, MOT and mileage since last MOT is usually a good indicator of the bikes reliability.

the bike was a Honda FMX650 from a Honda main dealer that I wanted for basic commuting duties.  I knew it was a single before walking in there, but the salesman insisted it was a twin on account of the two pipes coming out of the cylinder head!?!?

I've learned a lot about bikes since those early dealer experiences and it's private all the way for me now.