He was a bit of a hoarder so the place is quite disorganised and there's a lot of old hi-fi equipment. I'm thinking removing personal stuff (photos, etc), then minimum tidying... Would a charity then come in and help themselves to anything they could sell?
If he has anything of particular value maybe get a specialist in. e.g.a mate of mine who deals in second hand records regularly values and buys up collections in this situation.
very much that. what may appear to many to be a pile of old tat can, to the right sort of collector, be valuable. for example (in my line of country) a box of 1920s tram tickets might appear to be many to be tat, but if each individual ticket is worth a few pounds if you offer it to the right people, it's worth not overlooking.
things like old phone directories / street directories are quite valuable now for local / family history research.
and so on.
Johnny Vodka - is it practical to discuss this with dad? while some collectors have an over-optimistic idea of the value of their stuff, he might know what's what, and (if relevant) know what dealers and / or museums to talk to, and whether his preference is to prioritise 'good home' rather than maximum cash.
if any stuff is museum-worthy then museums will often accept collections as long as the person giving it is happy with the idea of anything that duplicates any existing items in their collection being sold on.
having said that, many charity shops are a bit more switched on to this sort of thing than they used to be, and will try and get a fair price for stuff for their funds rather than flog stuff off for pence and let someone else profit.
I think they wouldn't take white/electrical goods though.
certainly some BHF shops (the big ones that do furniture etc) will handle electrical goods - maybe not the small ones that do the traditional clothes / books etc.
Oxfam also have some specialist music shops, the one in Reading handles old hi-fi as well.