Is it a crime going thought red lights and hold on cars back? Can i get fined?

It's definitely illegal going through red lights. How you decide whether to jump or not is down to you, I find with experience you get better but don't get too cocky. Sometimes it's safer, sometimes more dangerous, every situation's different.

RE: Holding on cars... It's alot more tricky than it looks and highly dangerous. I've tried it a few times and each time wimped out pretty quickly. I'm sure there are a few seasoned pros kicking around this forum, but you're more likely to see this in the States, it seems.

Holding onto cars is definitely against the Highway Code, and the police would probably give you a MASSIVE bollocking if they caught you. As far as prosecution, they could get you for 'cycling furiously'.

Excerpted from 'Cycling and the law' on bike for all website
http://www.bikeforall.net/content/cycling_and_the_law.php

"CYCLING FURIOUSLY?
It's an in-joke in cycling that cyclists can't be booked for speeding but can be fined for "pedalling furiously." Many cyclists list being cited for "cycling furiously" as one of their life ambitions. Professor David S. Wall, Head of the University of Leeds Law School, a professor of criminal justice lists his hobby as: Cycling (Furiously)

However, these legal eagles say they have been unable to find a a reference to such a cycling offence in Blackstone's Criminal Practice or in Halsbury's Laws of England.

Which is odd, as Christopher McKenzie, an Australian barrister, pointed Bikeforall to these cases: Taylor v. Goodwin (1879) 4 QBD 228, a case where the Queen's Bench Division held, on appeal, that a cyclist was appropriately convicted by a magistrate for furious riding of a bicycle. The dicta of Justice Melor in the case has been cited and followed in a number of cases since: see, for example, Smith v. Kynnersley [1903] 1 KB 788 (cyclist not liable to pay bridge toll) and Corkery v. Carpenter [1951] I KB 102 (cyclist liable for offence where cycling drunk).

Although a legal eagle searching Blackstones will not find a specific offence of "furious cycling", cyclists can nonetheless be convicted for "wanton and furious driving".

The wording of S35 of the Offences Against the Person Act 1861 (as amended by the Criminal Justice Act 1948 (c. 58), s. 1(2)) is as follows:

“35. Drivers of carriages injuring persons by furious driving Whosoever, having the charge of any carriage or vehicle, shall by wanton or furious driving or racing, or other wilful misconduct, or by wilful neglect, do or cause to be done any bodily harm to any person whatsoever, shall be guilty of a misdemeanor, and being convicted thereof shall be liable, at the discretion of the court, to be imprisoned for any term not exceeding two years.”"

I got caught going up Glouchster place a few years back on a bendy bus doing some serious speed. They pulled up beside me I gave them a puzzled look and then bungied off and done a quick one round the roundabout. I'm an idiot. So don't do it.