Log into your online account and the offer is on the first page.
It appears this is online only and probably only beneficial if you are putting in a larger order because of the normal delivery costs (£3.00 upwards). However, if you combine it with some of the discount vouchers attached to this post, you can make even more savings.
The cheapest way to get the 300 Clubcard points is by ordering the following:
Daffodils Bunch £1.00
6 Cadbury Cream Eggs (BOGOF) £2.49
Tesco Easter 6 Fairy Cakes £1.19
Tesco 9 Mini Crispy Nests £1.29
Tesco 4 Hot Cross Buns £1.19
The total of these items comes to £7.10, but the 300 points can be used to get discounts of up to £12 from Clubcard deals.