I think as long as you have above a 6 in English lang, maths and science then its fine but you have to apply carefully as ‘top universities’ like UCL would probably reject you for your GCSE grades (they did to my friend). Make sure to get 3As for predicted, do good in your ucat and resit English language this summer to get a 6. Maybe some unis will be fine with the 5 in English language. And if you don’t manage to go straight after sixth form you can take a gap year and reapply or you can do another degree like dental hygiene/ biomed and then apply to dentistry. So yes it is realistic.