There is no interest with stocks and shares, the funds grow over time, which is where your gain is made. If you pick the funds well, overall charges should be less than 1%, and gains higher than that per year, on average, over time, although you do have to look over the long term, not short term. So 5 years or more.
Some of my funds have grown by anything from 100-300% over 10-15 years, so doubling / quadrupling my initial investments. Others have grown but by lower amounts.
One fund has dropped long term, but I did invest a lump sum, at height of the dotcom bubble and it has never re-gained what it lost. Hence why now all investments are done monthly.
The Hargreaves Lansdown site has a lot of information, on all different funds available, their charges, the gains made over previous years etc. HL aren't the cheapest 'supermarket' and some funds have higher charges generally, esp those from top companies such as Fidelity, Jupiter etc, but with a bit of research you can hopefully find some funds with low charges and good potential growth.
Just make sure you drip feed he money monthly!