Hey, as a person who just went through all of this a few months ago (I created a trident weapon) I can feel the frustration. Especially if this is your first boffer weapon.
I went with 1" and mine passed. I felt like 1.25" was too thick as well. All I can say is if you're going to push to the maximum length of the body spear to use 1.25" is a very good idea; however, it may not feel right for everyone. They recommend that because the longer the weapon the more likely it is to be "wobbly" or not as straight and that can cause issues with accurate poking of the weapon or general safety of it breaking.
The best advice I have is if you go with 1" is to make sure that it doesn't wobble if only a little because no matter what to use a 'safe' core it probably will a little, but should not be obvious. If need be, make the boffer end longer so the weight isn't all on the end and is more even throughout.
As I don't live in London I am unsure of a good place. But I can say that there are plenty of types that people use and it really depends. Home Depot has most of what you will need, if not all.
I used a "safety mat for kids" type of foam that you put on a floor as it was hard but squishy and used bed 'memory' foam as the boffers.
Pool noodles are fine and yes they can be rough, some people use sponges at the tips of their weapon instead of the foam like I did. Just make sure to poke holes in the boffer end with a pin or the like so it can "breathe" if that makes sense. A pool noodle may have issue getting around a 1" core pipe though and so you may need to find an alternative.
edit: the multi-layer foam pipe insulation will definitely suffice, but I would recommend doubling it up if that makes sense. So you would need 3. One goes directly on, another on that but it won't reach all the way around so the third you cut out a strip to fill the gap. The nice thing is this may create a cool looking design once it is all duct taped over
If you choose to go less than 1.25 it can be risky, just ensure it doesn't whip/wobble/bend.
I went with 1" and mine passed. I felt like 1.25" was too thick as well. All I can say is if you're going to push to the maximum length of the body spear to use 1.25" is a very good idea; however, it may not feel right for everyone. They recommend that because the longer the weapon the more likely it is to be "wobbly" or not as straight and that can cause issues with accurate poking of the weapon or general safety of it breaking.
The best advice I have is if you go with 1" is to make sure that it doesn't wobble if only a little because no matter what to use a 'safe' core it probably will a little, but should not be obvious. If need be, make the boffer end longer so the weight isn't all on the end and is more even throughout.
As I don't live in London I am unsure of a good place. But I can say that there are plenty of types that people use and it really depends. Home Depot has most of what you will need, if not all.
I used a "safety mat for kids" type of foam that you put on a floor as it was hard but squishy and used bed 'memory' foam as the boffers.
Pool noodles are fine and yes they can be rough, some people use sponges at the tips of their weapon instead of the foam like I did. Just make sure to poke holes in the boffer end with a pin or the like so it can "breathe" if that makes sense. A pool noodle may have issue getting around a 1" core pipe though and so you may need to find an alternative.
edit: the multi-layer foam pipe insulation will definitely suffice, but I would recommend doubling it up if that makes sense. So you would need 3. One goes directly on, another on that but it won't reach all the way around so the third you cut out a strip to fill the gap. The nice thing is this may create a cool looking design once it is all duct taped over
If you choose to go less than 1.25 it can be risky, just ensure it doesn't whip/wobble/bend.