The British Medical Association quotes a shortage of 50,000 doctors: https://www.bma.org.uk/bma-media-centre/nhs-short-of-50-000-...

There's an amazing chart here: https://www.bma.org.uk/advice-and-support/nhs-delivery-and-w... which shows the "Practising doctors per 1,000 inhabitants: England, UK and OECD EU nations". The UK is 16th out of 19.