There are typically two schools of thought on the topic of using a filter as you're suggesting:
1) Put a £50 filter on the front of your expensive lens to protect it. If you bash it, you've only lost £50.
2) If you've spent a lot of money on an expensive lens, why reduce the optical quality by putting a £50 piece of glass on the front of it?
Personally, I'm tending more towards 2). In my experience, the bigger lenses tend to have sufficient protection with a lens hood anyway. Also, in some 30 years of photography, I've never yet managed to scratch or damage a lens (he says, frantically searching for a piece of wood to touch!) Maybe I'm just lucky, but I suspect I'm in the majority.
My only advice would be, if you are going to put a filter on, buy the absolute best you can (your choice looks to be a good one).
Time flies like an arrow. Fruit flies like a banana!