I would try and get a d25 box, I’m 17 stone and it’s stable as they come even with the legs at full extension. If it can take my weight you’ll be easily ok.
I have a d25 st competition in black, but they are now over £500 and closer to £600.
I haven’t seen one, and not sure what the difference is with the st boxes, but RIVE are doing a d25 competition club box that’s £429 at rrp.
Go for a silver box, the trays are cheaper and also crop up more often on here and ebay. Expect to pay about 30-35 for a second hand winder tray though.
I would also go for fosters over nathans. While nathans of derby is the rive importer, he only sells things at full rpp whereas fosters, last time I looked, knock 10% off the rrp’s so you can save yourself money that way.