Some long winded factual detail about what the court can do. Non of it is a reflection of what might happen in your case, and actually I doubt enforcement powers are widely used at all. I am not a lawyer and am a rusty brained SAHM for a few years so take this into consideration... Lots of detail sorry but I'm glad of the distraction today!
Court has power to imprison (and change the residence arrangements) and/or fine the non compliant parent. These powers are rarely - I'd say never but there are probably some very rare examples - used as wouldn't be seen to be in child's best interests.
In the last 5 years any contact order made or varied should, I believe, have a warning notice attached that should inform that, if the order is not complied with, an enforcement order could be made. If your exPs original contact order was made in the last five years you should be able to read the wording of this warning on your copy.
Your exP would have to apply for an enforcement order. An order made could require you to complete up to 200 hours community service. He could also apply for financial compensation for loss incurred, eg, if a holiday was missed as a result of the non-compliance.
A judge can also require a parent to attend mediation or a parenting class if he thinks helpful.
Court Service leaflets CB5 and CB1 might be useful for you to read.
Re representing yourself, you can actually ask the court to have a friend with you, known as a Mackenzie friend. They can't address the court, but can help you take notes etc, and generally support you, make it less daunting. Again, I emphasise I'm no expert on this but worth checking out. I think there will be more and more people representing themselves in the future.