I think prices will drop a little over the winter as they usually do, but probably not by that much and there'll be correspondingly less on the market (plus I always think winter with the short days and having to stable overnight etc is a bad time to be getting a new horse anyway) so if you find something today that fits the bill I don't think you'd be silly to go for it at all, I doubt you'll be saving yourself more than a few hundred pounds max, and if you delay you could well end up having a frustrating winter going here there and everywhere seeing unsuitable or too expensive horses.
As others have said don't assume that because you're 'only' after a safe and sensible hack, not a competition horse, that necessarily means there's less demand/more on the market, I'd say the reverse, particularly since lockdown and all the riding schools closing etc every man and his dog wants their own horse to potter about on, whereas with competitions off and the pros losing their income, actually the competition market is probably more static.
Not accusing you of being a novice or an idiot, but it is a fact that in this country for the last decade or more no-one has been deliberately breeding nice 'average Joe' horses for the leisure market on a commercial scale (because it would have been financial lunacy to do so), until Brexit and lockdown there was enough supply from Ireland (supplemented with cast off sports horses that didn't make the grade, ex racers, indiscriminately bred cobs etc) to meet demand, but with the lockdown induced leap in desire for ownership plus the turning off (to some extent) of the taps of nice young ISH/Connie/Irish cob types coming over the water cheaply, you are now looking at too many buyers competing for too few horses hence prices being high. While I too go 
when I hear of someone paying £5k+ for a not particularly special 5 year old cob, that price is basically a reflection now of the true costs of breeding, raising and training a nice 'average' animal ready for an a amateur owner in this country - costs which if you think about it, are really not that much less for an ordinary horse, a cob or native cross type say, than for a high-powered WB, yes OK the stud fee for a cob/native stallion is probably virtually nil compared to a few k for a competition proven/graded WB, but after that the bulk of the costs and work, vets bills, foaling the mare, grazing and feeding the youngstock, breaking in and bringing on etc are virtually the same or perhaps even more costly/hard work if you want to the horse to be safe, calm and not a tricky/professionals ride which you might accept in a competition youngster... I know you probably aren't after a youngster so you may think what's she on about talking about youngstock, but just trying to illustrate that with any commodity on the market (sorry to refer to horses as commodities but when they are being bought and sold that's what they are) you have to look at the base costs of 'production'/obtaining and readying the animal and what people are prepared to pay and basically, unless you have a low cost source of supply and/or low demand, prices will rise, and that includes older/proven horses as well as youngsters since the price of a 5 year old will directly influence the price of a 7yo and so on...
As Please says that doesn't mean you won't find something particularly if you are happy with the odd quirk or minor health issue but you need to be patient, prepared to pay a bit more than you would have for the same animal 5 years ago and try out plenty before you find the right one! Hence me saying if you find the right one now don't let him/her go in the hopes of saving a few quid come the winter. As unis seem to be actually going back this year you might well find a nice teenagers horse being sold on about now as owner is off to uni in September, for instance?