[georg]

is builders lime the same as garden lime can it be used on an allotment
where dung has been spread

[Trillium]

Some people have used it, but if you're not VERY familiar with handling it, it's best not to use builders lime on veg soil. This is hydrated lime, Calcium Hydroxide, and can easily burn both you and the soil if not properly handled. Best to stick with garden lime formulated to be kinder to soil and also contain more useable elements by soil and plants.

[Salmo]

Answer to question 1
Garden lime is crushed limestone or chalk. Builders lime is hydrated lime and is a very fine powder. Because it is so fine it tends to blow in the wind and is unpleasant in the eyes. You can use either on your soil.

Because hydrated lime is so fine it is readily available and is quick acting.  For this reason you will need to apply only about half the amount to get the same effect on the acidity of the soil. It is often used on agricultural/horticultural crops showing symptoms of acidity as a quick fix.

Ground limestone is coarser and more pleasant to handle. It reacts in the soil for up to 3 years depending on how fine it is.

Before liming you should always do a lime test. Suggest that you read up under fertilizers elswhere on this site for the amounts required. If you overlime, easy on light soil, you may make some elements unavailable to the plants, notably manganese.

Answer to question 2
You should apply lime and manure seperately as the reaction between the lime and the acids in the manure makes much of the nitrogen in the manure soluble and rain can then leech it out.
Preferably apply lime and manure in different parts of the rotation. If you have to apply both in the same part of the rotation apply lime in the Autumn and work it in and then manure in the Spring.