~£1400 in invoicing late fees, is it worth the attempt in collecting?

Basic Info:

Based in England, I was self employed providing medical cover at events, nightclubs etc. Now also work under several companies still doing occasional work. When I first started, I just worked for 1 company, the company this post relates to. This is has happen all within the last 4 years

Company Info:

Small ltd company owned by an individual. When I first started, the starter email states all invoices will be paid within 30 days. The director/owner has worked with questionable individuals, has a (heard from other colleagues, unconfirmed) sexual offence investigation and is generally viewed unsafe by the industry.

Main query

For the first year or so, the company was pretty much always late on invoices. A few days late here and there, with the occasional lateness of 30-40 days. The interest adds up to nothing but with the compensation fees, I believe could invoice for up to £1400. Not all my invoices (the actual documentation) have accurate invoiced and due dates (I was new to invoicing + laziness to properly check meant I might've created the invoice the day of the work but not sent off for a week or two). I am basing the amount of the date actually sent and +30 days.

My questions are:

Would the request for compensation hold up with the incorrect invoicing dates?

Is it even worth attempting to collect, risking retaliation, when I've just started a new career in a different industry?

If I've missed any info, please ask