Actually, the relevant offence to charge might be the more rarely used Section 29 of the Offences Against the Person Act 1861 (my emphasis added):
29. Using explosives or corrosives with intent to do grievous bodily harm
Whosoever shall unlawfully and maliciously cause any gunpowder or other explosive substance to explode, or send or deliver to, or cause to be taken or received by any person, any explosive substance or any other dangerous or noxious thing, or put or lay at any place, or cast or throw at or upon or otherwise apply to any person, any corrosive fluid or any destructive or explosive substance, with intent in any of the cases aforesaid to burn, maim, disfigure, or disable any person, or to do some grievous bodily harm to any person shall, whether any bodily injury be effected or not, be guilty of an offence, and being convicted thereof shall be liable, at the discretion of the court, to imprisonment for life… .
Two significant points about this:
1. Unlike the more commonly used offences of Assault/ABH/GBH this is a 'conduct' crime rather than a 'result' crime, so the fact that the victim was not seriously injured does not affect the applicability of s.29.
2. The Terrorism Act 2006 makes reference to s.29 OAPA 1861, so it is still seen as a specific chargeable offence and is deemed to be of a terrorist nature.