+1 Ravima's post.
The solicitor is right about the party and party costs not covering the submission to PIAB.
He does not have a lien on your damages cheque.
Actually, the solicitor almost certainly has a lien of sorts if he\she has issued a proper engagement letter and got the client to sign it. My engagement letter, always signed by the client, authorises me to lodge their settlement cheque, to discharge any outlays and to retain (but not take) the amount of my fee until the final amount is settled. I also include an explanation of the resolution mechanisms available if there is a disagreement on the fee.
Early in my career - just as an experiment - I handed over compensation cheques without deduction.
A typical scenario (in a straightforward case settled at PIAB stage) might be that:
a) I had secured maybe €12k in a settlement cheque;
b) I had secured maybe €1k+VAT+Outlay from the defence insurer against a bill of maybe €1200+VAT
c) I would hand over the settlement cheque along with the bill showing the balance due (in this typical scenario, €200+VAT) and tell the client to drop in the money as soon as they had banked their cheque.
The first three such clients stiffed me. I do very little of this type of work, so this was over a period of maybe a year. Over a drink, I told an older colleague that I was going to run the sequence to 10 clients, just to be sure.
He told me not to bother - that he would bet his house on all ten stiffing me.
He also pointed out the rather obvious:- that if you send a client out the door owing you money, you are most unlikely to get repeat business from that client or indeed the client's family.
He was right on both counts. So I stopped the experiment.