We enjoyed our stay at St Athans. For what you are paying- it’s a perfectly lovely stay with clean shared bathrooms which I was nervous about, quiet, walkable and friendly staff. Our only downside was that we stayed during the historical heatwave of the UK so although there was a window, we didn’t get much relief. Fans were offered to us the last night but also know this is very atypical of London and can’t hold the weather against them.
For a quick stay in nice area of London and just passing through- it’s a great budget option!