1882 were nearly all minted by Heatons and therefore carry the H - a few were minted in London (just to test the new electronic presses?) and are very rare.
I'm baffled by the George III coins though - pennies weren't minted until 1797, "cartwheel" type. There's no 1773 or 1775 pennies, but there were halfpennies which are noticeably smaller than bun pennies unlike your 1773. The 1775 looks very wrong and is probably an 'evasion' type, i.e. a contemporary forgery produced in the US. The 1773 "penny" looks more like a genuine halfpenny should apart from the size , but is also probably wrong - REX is wider spaced than on a genuine example.