£600 isn't going to cut it I'm afraid. Check this TA link just to get a feel. Some are a bit dated but you'll get the gist. Then try the respective sites & see if you can configure something in budget.
i5-i7, 1 or 2tb with 16gb of ram...well i5 should do what he wants, as well as 16gb RAM, but not sure he needs 2tb...check prices to see if it's affordable. SSDs have dropped in price but not sure of cost of 2tb. Don't get AMD, Intel are better in my opinion.