@Gillian166
Yes, the bleeding through can be an issue with furniture that has a very dark finish, e.g. the faux mahogany type. Most of the stuff I have chalk painted has been a lighter wood and I've had no bleed through. I did, however, paint a nest of faux mahogany tables a few years ago and there has also not been any bleed through.
To be on the safe side though, you can always use a special primer-sealer (I read that Zinsser make the best ones for this) before chalk painting, which is a lot less fuss than sanding/stripping in my opinion. I don't mind doing a light sanding, but stripping furniture is a pain in the backside. I have sometimes stripped and restrained the top of a sideboard and painted the rest, as I quite like that look, but that would always be my least favourite part and I couldn't wait to get past that and start the painting!
Re up cycling furniture as a business, I think it probably depends on the location and the market there. If it was something I was seriously considering, I would do a lot more research on that and the different outlets for selling.
People in London can pay a lot for vintage furniture. I saw a stall in Greenwich market selling painted furniture for some pretty hefty prices and pieces also going for quite a bit on Ebay (not just in London) as long as the seller started the bids very low. I saw some listings on Etsy where the prices were very high and pieces were selling. They had been done to a very high standard with a lot of detail and people seemed prepared to pay for that. One of the things that put me off is that you have to include postage at a fixed price, and I know that the costs for this can really vary depending on where it's going. It's not going to cost the same to send a piece of furniture to a buyer in London as it is to Edinburgh!
It's crucial of course to buy the pieces for a very low price to start with and I've always been good at finding bargains, but it's not really feasible without a car and I also don't have the space to store/work on the pieces. I do love the idea though. I really had to stop myself yesterday from picking up a sold wood coffee table that some neighbours had chucked out. Some pretty wealthy people live in that apartment building (I can tell from the cars parked outside) and they keep throwing perfectly good, quite expensive furniture out! Last time, I picked up a card table, but I still haven't finished painting it 😞