£430 on a Btwin Triban 5 (full sora 9 speed which is a great groupset)
Then spend £145 on a pair of new Mavic Aksium wheels to go on it = perfect budget road bike for a whole bunch of money less than anything else.
Weak point of any budget road bike (just about anything under £1000) is the wheels. Just about all run on the cheapest of cheap joytech hubs, which usually aren’t remotely smooth of the box, freehubs commonly become permanently free after a very short period of time, then laced to a no name non eyeletted rim with naff spokes. Fine for very occasional use at entry level, but any sort of mileage or weather on them and your back at the shop buying new wheels. Hence just get Aksiums or shimano RS right away, you’ll likely get a good discount too