ORTHOPAEDIC SURGEON REQUREMENTS UK URGENT?

Orthopaedic surgery is a medical specialty, so you need to first get into med school, graduate with a degree in medicine (one of the many variants of MBBS, assuming you study medicine at undergraduate level in the usual fashion), complete your internship ('foundation' stage, or what you're calling 'residency') and qualify to practise, then undertake specialty training (what you're referring to as 'fellowship') in your chosen field and finally qualify as a specialist in that.

In order to get into med school in the UK, the most common A-level subject requirement is chemistry, followed by biology; most med schools require both. Some also require either maths or physics as your third, so if you take all three you can apply to every med school in the country. Assuming, that is, you get AAA or better, as that is the minimum grade requirement for every med school, and some want at least one A*.

You will also need an above-average score in either of the aptitude tests, UKCAT or BMAT, depending on which med school you apply to. And you need some relevant work experience, and evidence of interest in and commitment to the medical field, eg. by demonstrable knowledge of how the profession works, what are some current issues in medicine/healthcare, etc.

There are no particular GCSE requirements for most med schools, although some do require at least grade C or B in English (and often maths, if you don't take it at A-level). Some also require a minimum number of GCSE Level 2 passes (ie. grade C or better), most commonly either five or eight, but that's not too much of an issue as you're almost guaranteed to have those anyway. Where GCSEs do matter is that you're highly unlikely to be able to take A-level sciences unless you had GCSE triple or at the very least double science, and got A/A* in them. So in that sense indirectly you need good GCSE science grades, not for the med school as such but rather for sixth form.

PS: Just to clarify, the model you're describing (degree plus 4-5 years med school) is the US/Canadian one, where medicine is only taught at postgraduate level. Here in the UK, and indeed every other country in the world, medicine is available as undergraduate subject, so you go straight from secondary school (A-levels, or whatever you're taking) to study medicine, ie. no need for a 'pre-med' degree first.

PPS: Also worth pointing out that your timings are quite a bit off, especially for the undergraduate model. The typical duration of your studies and training would be roughly: 6 years of med school (can be 5-7, depending), followed by 1-2 years of internship, followed by any number of years of specialty training (depending on what you want to specialise in and whether you go for any sub-specialty) but typically 2-5 years, so in total about 10-12 years from start to finish.