I am afraid that you won't get much sympathy here, on the basis of
after I filed my tax I went abroad in october and I spent all my money
as you are expected to have made provision for the payment of your liability. I am not surprised that HMRC were unhappy with your offer of £100 with a non-specific promise to pay the balance "once you catch up with your finances".
In reality you probably need to borrow £5,000 to pay HMRC. Remember that surcharge of 5% applies to any amount still unpaid at 29 February, and that interest is charged on late payment. HMRC used to be quite generous with time to pay arrangements, but now generally only help people/businesses who are having payment problems through no fault of their own. Sorry if all that sounds unsympathetic, but it's the reality of the situation.
but will this affect my credit rating and will it be an legal action against me for not paying the full amount on time
Their first action is likely to be distraint - seizing your assets to be sold at auction. If that is not possible or if it fails, they will take action in the County Court. And that could result in a CCJ and yes it would affect your credit rating.