Both calibres are very good, I have and used both extensively over the years, also use 7mm-08 and 6.5x284 again superb calibres, and would not change. But your question has a couple of other considerations. Do you want a rifle a rifle that is both easy to get factory ammo anywhere, with plenty of manufacturer options? Easy to learn how to reload well. Well capable of anything in the UK? Not too exotic, hence good resale value if you decide to change. A rifle that you can easily compliment as and when you want to expand. Can take most places in the world, and within reason never be too far out of place. Ok a couple of countries frown on military calibres.
If you can shoot your friends 30-06 well, then go with that. But if you plan to stay in UK, and do not wish to use anything heavier than 165grains go with a good old 308, and that can be said with no bias on my part, because if I was to sell all my rifles, and have only one I would keep the 30-06 as this gives me more options when abroad.
Good luck withe the DSC 1, and enjoy choosing. Bet you don't finish with only one rifle!!!
ATB
HL