Cheers chaps. Collect+ will cover up to £300 assuming you buy the extra cover.
Interestingly I just found the the Royal Mail restricted goods list:
Gases including flammable, non-flammable, toxic and compressed
gases, new, used and empty gas cylinders, butane, ethane, refills for lighters, fire extinguishers and scuba tanks, life jackets, nitrogen dioxide and carbon dioxide canisters (culinary foaming devices & soda stream),
1. All flammable compressed gases are prohibited e.g. blowlamps; butane; lighters and refills containing flammable liquid or gas; ethane; gas cylinders for camping stoves; hydrogen; methane and propane.
2. All toxic compressed gases are prohibited e.g. chlorine; fluorine etc.
3. All non-flammable compressed gases are prohibited e.g. air bags; scuba tanks, carbon dioxide; fire extinguishers; neon and nitrogen.
Which is pretty much the same as collect+. my doddle, myHermes etc. I think the intent is that very high pressure thinks like fire extinguishers etc are deemed too risky.
The tiny amount of air in a fork or shock shouldn’t fall into this description. Otherwise something as simple as an empty water bottle wouldn’t be permissible. Maybe its only royal mail that x-ray packages so that they can check packages.