When I see 105.25% allocation, I'm going to guess that there's also a 5% bid/offer spread - effectively a charge. You can check this. One cancels the other out. 105.25% x 95% = 99.99%. If that's the case your husband is paying €3.49 per month and 0.75% per year.
That's okay if it's a small pension scheme. If it's a large scheme (say 100 members+), the employer could get a better deal but that's up to them to look.
His only option for an AVC outside the employer's scheme is to set up his own AVC PRSA. Best charges he's going to get with that are 100% investment and 1% of the fund per year, or maybe 0.9% for Vanguard funds.
If you're both paying high-rate tax, could you max out your AVCs instead? Maybe you are already.