don't buy supersonics, they tear like single ply Andrex. Latex aren't repairable but you'll never hole them so it doesn't matter, I went through 5 supersonics in under 6 months, i hven't lost a latex tube in 18 months. You do need to fill them every ride though…
I'm with Cynic-al, gte your contact points sorted, saddle, pedals, shoes and bars. Ensure you have the saddle and bars at exactly the right angles and heights, a few mm and few degrees here and there make the difference between a bike you can only ride for 30 miles and one that you do centuries on with comfort.