Like Symphony, my preferred choice of coating would also be Ronseal. However Ant is also very knowledgeable on this subject so his advice will be good. Going back to the point about Ronseal, it does tend to dry quite quickly, particularly on freshly sanded bare wood on warm days, so my advice if you do use Ronseal is to choose a cool day in order to extend the drying time as much as possible, and work as quickly as you can so that in the application of the Ronseal you can be always working from a “wet” edge. Keeping the edge wet enables you to blend in the coating better than if you should allow one part to dry before you have finished the application to the entire area. Once one part dries, any over coating of that area tends to show up as a more intense colour than at areas where you had a wet edge and were able to blend in the join. Have a practice on a separate piece of wood, and you will see what I mean if you let the edge dry in one part before the entire area has been coated.
Good luck with the job.