This is the complete list of permitted items under schedule 4, it says somatotropin (i.e HGH) under No. 4, so you are OK.
Part II
Controlled Drugs Excepted From the Prohibition on Possession when in the Form of a Medicinal Product; Excluded from the Application of Offences Arising from the Prohibition on Importation and Exportation when Imported or Exported in the Form of a Medicinal Product by any Person for Administration to Himself; and Subject to the Requirements of Regulations 22, 23, 26 and 27
1
The following substances, namely—
[4-Androstene-3, 17-dione] Methenolone
[5-Androstene-3, 17 diol] Methyltestosterone
Atamestane Metribolone
Bolandiol Mibolerone
Bolasterone Nandrolone
Bolazine [19-Nor-4-Androstene-3, 17-dione]
Boldenone [19-Nor-5-Androstene-3, 17 diol]
Bolenol Norboletone
Bolmantalate Norclostebol
Calusterone Norethandrolone
4-Chloromethandienone Ovandrotone
Clostebol Oxabolone
Drostanolone Oxandrolone
Enestebol Oxymesterone
Epitiostanol Oxymetholone
Ethyloestrenol Prasterone
Fluoxymesterone Propetandrol
Formebolone Quinbolone
Furazabol Roxibolone
Mebolazine Silandrone
Mepitiostane Stanolone
Mesabolone Stanozolol
Mestanolone Stenbolone
Mesterolone Testosterone
Methandienone Thiomesterone
Methandriol Trenbolone
2
Any compound (not being Trilostane or a compound for the time being specified in paragraph 1 of this Part of this Schedule) structurally derived from 17-hydroxyandrostan-3-one or from 17-hydroxyestran-3-one by modification in any of the following ways, that is to say -
(a) by further substitution at position 17 by a methyl or ethyl group;
(b) by substitution to any extent at one or more of positions 1, 2, 4, 6, 7, 9, 11 or 16, but at no other position;
(c) by unsaturation in the carbocyclic ring system to any extent, provided that there are no more than two ethylenic bonds in any one carbocyclic ring;
(d) by fusion of ring A with a heterocyclic system.
3
Any substance which is an ester or ether (or, where more than one hydroxyl function is available, both an ester and an ether) of a substance specified in paragraph 1 or described in paragraph 2 of this Part of this Schedule.
4
The following substances, namely—
Chorionic Gonadotrophin (HCG)
Clenbuterol
Non-human chorionic gonadotrophin
Somatotropin
Somatrem
Somatropin
5
Any stereoisomeric form of a substance specified or described in any of paragraphs 1 to 4 of this Part of this Schedule.
6
Any salt of a substance specified or described in any of paragraphs 1 to 5 of this Part of this Schedule.