Thanks ladies for advice/comments.
Kathleen, I've checked out that clip comb, looks intriguing, may get one of those for future use.
As it turned out I went to a local, low key, backstreet hairdressers for a wet cut, discount for new clients so a very reasonable £12. Very quick visit, 4 inches lopped off, square cut, all one length, centre parting (no fringe) and it's made all the difference. Two years on, I've nearly grown out a disastrous set of highlights that were more like block colour.
Next decision will be colour - it's a very flat, dark-ish mousy non-colour with about 20% grey - I only ever do the wash in, wash out colours, never attempt the permanent ones - maybe T-section low-lights, tint, no bleach at this same salon.
Read that Joanne Lumley cuts and colours her own hair - really?!