Dan, I think B&Q may disappoint you. I’ve been there every month or so for the past year and often have looked for stain/quality lacquer and polyurethane finishes…stains you may come up empty. You need a quality topcoat on top of any stain you use, anyway.
I ended up buying a German-branded water-based poly but it’s expensive and need to brush or roll on 4-5 coats (but no scuff sanding is needed) to get good coverage and protection. So if you see a brand that has only German and Chinese, that’s it. I honestly think you’d be better off Taobao’ing some stain as I haven’t seen anything of name-brand/English label. They no doubt have stain available somewhere in Chengdu as installers/remodelers use it here, but I’m not sure where! Most people spray on finishes and even stain, but I haven’t yet invested in a compressor to do so. Wish I could help you out more!