Rabbit Leg,
We can all see you have made 93 posts, and have been here for a while but due to the problems with search engine, no one can find more than the last three without considerable effort. It means that most folks couldn't go back to see what sort of experience you might have, even if they wanted to.
If you think that the members who posted what they (and I) thought was reasonable, well meant and helpful advice were rude and patronizing, and worse, that you think that is the norm here...well, I am sorry, not much anyone can say or do. My experience is that if you don't tell folk at an archery club or shop any more than you told us, you will get similar advice.
I used to build bows for myself, and despite shooting most weeks for several years, I never got myself up to a 50lb bow. I handled 45lb and did use it for both field and stump shooting. You say that you have long arms, and that the bow in question is 50lb at 28", but what will it be at your draw length? If you have long arms, and need long arrows, you will be drawing the bow further and it will be higher poundage. Being a recurve will help with stacking, but even so you could be looking at several more lbs.
The two reasons that I wanted more lbs when I was shooting was that I wanted to get flatter trajectory for outdoor target archery, and I had ambitions of bow hunting in the US. At distances up to 25-30m, shooting big 5" feather three fletch arrows at stumps I didn't feel like I was under-bowed with 40lb. Field archery...yeah, a flatter trajectory would have been nice, but trajectory is about more than poundage. I could have done myself favours with better spine matched arrows, smaller fletchings, lighter string and a smoother shooting style.
Anyway, you want tough arrows. For a bow costing £124 that you are just going to stump shoot with, I would buy wooden arrows, or rather, I would buy shafts and make my own. I would look for Spruce, maybe Fir, 11/32. I think Ash would be too heavy, among other things. There are a lot of pages from US sources that discuss toughness of arrow wood. They stump shoot a lot more there as part of hunting practice. The only problem there is then matching the suggestions to UK sources. There are a surprising number of sources for wood shafts.
There is no doubt that carbon can be very tough, but they are expensive and my opinion is that they are an unjustifiable expense for the sort of shooting you describe.
Wood on the other hand, you can buy your own shafts and make up your own arrows. If you lose a point in a stump, some hot melt glue and a Bic can fix that. If the tip breaks, you may be able to fix that too when you get home. You can play with point weights pretty easily, changing the dynamic stiffness of your arrow. If you want a craft hobby you can turn wooden arrows into footed shafts with very few hand tools and some patience. I always got a kick shooting gear I had made myself.
When I did stump shooting I used a Judo Point, which reinforces the end of the shaft and didn't dig in far, also stopped me losing arrows so easily when I missed. I only had three with such points, and that was plenty to rove around with.
Best of luck.
I dont shoot anywhere near as much as I used to but 50 even then would be a push unless shooting weekly. Dont get me wrong I can pickup my 70lb bow now and lose arrows, well a couple lol. 
