Hi there
I saw your callout on a previous thread, really sorry about the delay in replying, it's been busy as hell in the house!
I personally think your ex is being unreasonable. It has been HIS decision to move 1/2 way across the world (when he really doesn't have any need to), my view is that both parents should stay within close locality (indeed in some states of the US this is a condition of separation if there is to be a shared care arrangement).
Contact when one parent lives overseas is always problematic and whilst it is impractical for contact to occur as frequently as, say, on a monthly basis due to the distance.
Normally in situations like this nearly all holidays would be for the child to have contact with the overseas parent though.
I think his threats are unlikely to be successful but yes, costs rapidly ramp up in a contact order dispute. You would have no problem self-representing yourself as a Litigant In Person (LIP) with the aid of a McKenzie friend. I would strongly recommend you pop along to your local Families Need Fathers meeting to get some advice. Look up your local FNF branch on the web and give your local branch chair a call/email. FNF, despite the name, are a gender-neutral national charity and help out all parents/carers, indeed about 1/4 of our membership is female (including female parents/carers/grandparents/new partners).
It's worthwhile engaging in dialogue - all by letter (keeping copies for yourself) snet recorded delivery either to your ex's solicitors with your proposals and requesting discussion of the child matters at the local family Mediation services.
It's unlikely the ex will have submitted a C100 form as his proposals really are quite unrealistic.
In my mind it would be more reasonable for the first years contact to be in the UK for a couple of weeks. Especially as the children are 7 + 5. It's OK travelling to mainland europe at this age, but to australia is one hell of a jump in one go. Better to have initial contact in the UK and then a couple of weeks in australia in subsequent years.
It would be normal for the other parent who has relocated to pay for the travel and to organise it, he can either travel here to the UK or organise chaperones. I don't think it's reasonable for 60yr olds to be doing this, plus how many years are they going to be willing to do this? Not many I bet.
Contact in future years could be phased in for longer periods depending on the age of the children. All summer holidays is probably a bit too long - can the ex have contact during other holiday periods such as easter / half-term?
Hope this helps somewhat...