If his registered address is his home, he can claim travel to his place of work. If he claims the costs of running a vehicle, he can only claim the proportion of expenses (and capital allowances) that relates to "business" use not the proportion that relates to personal use. A good alternative is to keep a mileage log and claim 40p per mile (up to 10,000 miles) which allows for the capital cost of the vehicle.
He can claim 100% of mobile phone costs but only a proportion of home phone if he uses that for business - unless he has a dedicated line (which sounds unlikely).
He can also claim a "use of home as office" deduction if he does his paperwork at home. This would be a proportion of his rent or home costs, if he owns his own place.
He can claim the cost of "protective clothing" - but this only really covers steel-capped boots, overalls etc. I have some clients who claim "laundry costs" if they have jobs that mean they get very dirty.
Hope this helps. Check out the Revenue's website or their helpsheet "Notes for Self Employment" page SEN8 - which will give you other ideas.
And don't forget to include all his CIS25 vouchers.