This is just a standard court letter. Easy to deal with.
After the defence has been sent to the court, the Claimant should consider your defence and evaluate whether to continue or not. However you may see a couple of legal "tactics" being used. Some call them "tactics" while others see them as a continued abuse of the court system to confuse people further.
If you get a Directions Questionnaire from the Claimant's solicitor before you have had the chance to send in a defence, then continue to send the defence to the court - and then deal with the Directions Questionnaire.
How to fill in the Directions Questionnaire is here.
Notice of Proposed Allocation Example Form.