What weight is your bow and draw lenght?
Was gonna say......
You need to get your draw length and weight sorted first, I recommend Easton Arrows and advise you to go to their site and check out their arrow chart for correct spine. Easton are good arrows but they are widely available in the UK including on Ebay so if you do that you will likely find something that will suit.
Or better still, get yourself to an archery shop or to someone who knows
Compounds are not to be messed with BTW (apologies if this sounds patronising) they have so much stored energy and if you get the spine wrong, at best you will not get groups and likely have arrows all over the place at worse you can have a bow exploding because much too light an arrow is no better really than a dry fire and folk get killed with wheelie bow malfunctions every year!