cheap lean-to roof replacement

Hi looking to replace or improve an existing polycarbonate roof on a lean to. The existing structure is roughly 5.5m x 2m with a small flat roof of around 1m next to the building then a sloping polycarbonate roof which has six panels each about 1mx 1.5m that are glued together at the seams.

As well as being fairly dirty and blocking the light, the seams occasionally leak and offer next to no insulation making it cold in winter.

Looking for ideas to improve this roof relatively cheaply (~£1000)

Any experiences of different options would be very useful