Rule 8.4 covers what happens if the defendant fails to file an acknowledgement of service:
(1) This rule applies where –
(a) the defendant has failed to file an acknowledgment of service; and
(b) the time period for doing so has expired.
(2) The defendant may attend the hearing of the claim but may not take part in the hearing unless the court gives ...
You may file a motion for a continuance (here is a sample help page). You have to provide as much information as is required to persuade the judge to grant the continuance. Nobody knows exactly how much information that is, and probably only your lawyer (I assume you are doing this yourself) would have a reasonable idea. Simply saying "I can't cope"...