New allotment with heavy clay. how quickly can I amend?

[muddled]

Gypsum is s'posed to be very good too although not as easy to source.

I also have thick clay....I made a pizza oven out it! I find mulching heavily stops it turning to concrete in summer. Not walking on growing areas helps in the winter and 'turning over rough' to let the frost break it down also helps.

The absolute most difference I made though was to lay several inches of leaf mould on top at this time of year. The worms and weather pulled it down and the area I put it on was the only area fit for seeds the following spring. Worked so very much faster than the areas I manured.

[Kristen]

... the only area fit for seeds the following spring

I don't assume I will be able to get on mine, nor be able to sow direct, in the Spring, so I sow everything in pots etc. ready to transplant out when the soil is warm / safe to work!

For folk that sow direct it probably seems like a lot of faff (and not much good to anyone without a suitable greenhouse / conservatory), but it means I can sow seeds in the evening, after dark / work, without worrying about weather, and I don't get any delays due to foul weather / cold soil, and the potted plants will "hold" for a couple of weeks, come planting time, if good weather doesn't coincide with time off work